I like to call them Lost Cartographic Arts. Techniques, tools, and styles of mapmaking that, for whatever their various reasons, aren’t commonly seen anymore.
The lost cartographic art I’ll talk about today are isometric perspective and local oblique maps.
There may be a more proper term than ‘local oblique map’ to describe what I’m referring to: but the concept is simple. It’s a map with a non-planimetric perspective with a very limited (often city- or neighborhood-level) geographic extent.
There’s a lot of useful things that happen when you have a map with an oblique perspective. Most of all, viewers get to see the shape and height of buildings and other landmarks. With a top-down view, all viewers can see is the color and shape of the roof. Unless you are in a hang glider, this is not information you can use to identify a structure or navigate through an area. Obliques are great for navigating through a crowded place like a city, or just for getting the general feel for the layout or organization of a small area.
Web map services have recently realized this, and are competing to find ways to best recapture the utility of oblique views. Bing has ‘birds-eye’ aerial photographs that the user can toggle on; Google Maps has started commissioning a massive collection of 3D models of buildings that users can see; and, of course, Google also pioneered street-view capability which is indispensable for local-scale navigation.
If oblique views are so handy, why did they go away in the first place? The answer, I think, is honestly laziness.
Okay, maybe laziness isn’t quite the right word. The more eloquent explanation is that digital mapping technology simplified the production process of maps in general, but wasn’t cut out for the production of oblique perspective maps. From its inception GIS software uses a euclidean data structure; everything has an x and a y, and the z (height) just sorta gets flattened out. There are elevation datasets, but these tend to be for the ground only (no buildings), and the technology to 3D render a map (e.g. ArcScene) is a much more recent advancement (and one that is still rather primitive in the grand scheme of 3D modeling technology).
So, making an oblique-perspective map is one that requires a lot of manual labor, which is the sort of investment that most map producers aren’t willing to put in. So the whole art form unceremoniously faded into disuse.
ABOVE: Screenshot of ‘Simcity 2000’ - Maxis, 1993
Meanwhile, outside of cartographic realms, one form of oblique local was becoming very commonplace: isometric maps. If you want to get technical, isometric projection is a means of projecting 3D space into a two dimensional image wherein width, depth, and height are all at the same scale, and the three axes are spread 120 degrees from each other. The more understandable way to describe it is “it’s that angle that SimCity 2000 uses”. It’s one of those ‘you know it when you see it’ sorta things.
Isometry has been around for a long time- for over 500 years in Chinese art and over a century in western technical drawing. Where isometric perspective really entered the public consciousness, though, is in early computer graphics. It’s relatively easy to render using both vector graphics or good ol’ fashioned pixels. Early entertainment software in particular really took to isometric perspective, because it allowed the illusion of 3D space while being rendered using 2D tiles. Owing to this, isometry is one of the most common forms of representation in the pixel art community. (fun fact: before I was a cartographer or an illustrator, I was a pixel artist!)
There’s some curious wrinkles to the isometric view: first off, the height of objects obscures what’s behind them, potentially obscuring them entirely. There’s also some famously wacky illusions that happen when all 3 axes are all on the same scale: this is how we get things such as the Penrose stairs or Escher’s waterfall illusion.
Nevertheless, isometric perspective is a pretty attractive way to render a local-scale oblique; one that once again remains uncommon in Cartography largely because it’s less conventional and requires a bit more effort and knowledge to produce. Fortunately, “unconventional and labor-intensive” is this blog’s unspoken credo, so check back two weeks from now when I try my hand at an isometric map.
But first, next Sunday, it will be time for another map review. I’ll be tackling one from the world of Fine Art, so things might get a bit heady. It’ll be fun though! Tune in!